W02006/132511, describes a local area network wherein data frames from different transmission channels are combined. A device with a plurality of antennas is used to realize the different channels. U.S. Pat. No. 4,821,289 describes transmission of the same signal in a plurality of channels, in order to counter channel selective fading by processing data from the plurality of channels and selecting data that does not suffer from fading.
Typically, the signals from the channels need to be filtered extensively, to prevent interference other channels. In a band of channels of the same type, e.g. in a GSM band, UMTS band or a WIFI band these other channels could be of the same type, but near the edge of such a band, the other channels could be of a different type. Because the signal power in such other channels may vary widely, and may well exceed the power in the channel that is actually received, extensive filtering is used to prevent interference from such other channels. Digital signal processing may be used, wherein the filter operations of different channels may be performed in parallel or on a time division multiplexing basis.
Excessive power consumption is a problem of devices that process a plurality of parallel channels. Digital signal processing requires power in proportion to the number of signal processing instructions that have to be performed per time unit. Accordingly, power consumption typically increases with the number of channels and in proportion to the number of filter operations that have to be applied to channels individually.